Recently, a customer sent us an email and stated their SELECT button was always being pressed. We ran through the normal troubleshooting to isolate the issue to a particular component and then it dawned on me, I bet a connector is soldered on incorrectly.
When I was testing the PFS3 Hitbox EZ BUILD boards I had the same exact issue but couldn't figure out why for the life of me. After a lot of time, headaches, and probing with my Multimeter I realized I had soldered a connector on backwards! Specifically, the one where the L3/R3/Touch Click wire connects to the Universal Fighting Board.
If you solder it in backwards (for those who bring their own PCB to the table) you are connecting the TP CLICK signal directly to the GROUND plane on the EZ MOD board when the interlinking cable is connected. This tells the UFB that you are holding the TP CLICK button down the entire time! Since windows treats the UFB as a XBOX ONE controller by default, it thinks TP CLICK = SELECT.
If you don't get the UFB with your Panzer Fight Stick 3 kit, please be sure to solder the connectors like the graphic below or you too will have this issue.